From cell phones to sweeteners, it can seem like everything has been blamed for causing cancer at one point or another. Separating evidence from rumor isn't always easy. Here's what major health organizations say about eight of the most common questions.

1. Do artificial sweeteners cause cancer?

Artificial sweeteners — including saccharin, aspartame, acesulfame potassium, sucralose and neotame — are far sweeter than table sugar, so only small amounts are used. Early studies in rats linked saccharin to bladder cancer, but further research showed the mechanism involved doesn't apply to humans. According to the National Cancer Institute, there's no clear evidence that the sweeteners approved in the U.S. cause cancer in people. Research continues, and regulators periodically review new data.

2. Is cancer contagious?

No. You can't catch cancer from another person. Some infections, however, can raise the risk of certain cancers. Human papillomavirus (HPV), for example, is linked to cervical and other cancers, and HIV weakens the immune system in ways that make some cancers more likely. The infection alone usually isn't enough; other factors such as immune health, smoking and additional conditions play a role.

The rare exception involves organ or tissue transplants. Transplant-related cancer can occur, which is why doctors avoid using organs from donors with a history of cancer. According to the American Cancer Society, this happens in roughly 2 out of every 10,000 transplants.

3. Can surgery or a biopsy make cancer spread?

Cancer is dangerous largely because it can spread — into nearby tissue, to lymph nodes and to distant organs, a process called metastasis. But surgeons take specific precautions during biopsies and operations to keep the chance of spreading cancer cells extremely low, such as using separate instruments when removing tissue from different areas. The National Cancer Institute's overview of metastatic cancer explains how spread actually occurs.

4. Do cell phones cause cancer?

Cell phones communicate using radiofrequency (RF) waves, a form of non-ionizing radiation that falls between FM radio and microwaves in strength. Unlike X-rays, gamma rays and ultraviolet light, RF waves don't have enough energy to break the chemical bonds in DNA. Large studies have not found a consistent link between cell phone use and cancer. The International Agency for Research on Cancer lists RF fields as "possibly" carcinogenic based on limited evidence, and research is ongoing.

5. If cancer runs in my family, will I get it too?

Not necessarily. When several family members develop cancer, it's often because they share habits or environments — smoking, diet, activity levels — rather than an inherited gene. Only a minority of cancers are tied to inherited genetic changes. In those cases, what's passed down isn't cancer itself but a gene variant that raises risk. Healthy habits can lower risk either way, and people with a strong family history should talk to a doctor about screening and genetic counseling.

6. Is cancer a death sentence?

No. Cancer death rates in the U.S. have fallen steadily since the early 1990s thanks to better prevention, earlier detection and improved treatment. Five-year survival for some cancers — including many breast, prostate and thyroid cancers — is now 90% or higher, and overall five-year survival across all cancers is about two-thirds. These figures reflect large populations; an individual's outlook depends on cancer type, stage and other factors.

7. Does hair dye cause cancer?

There's no conclusive evidence that personal use of hair dye increases cancer risk. Some research suggests hairdressers and barbers, who are exposed to large amounts of dyes and chemicals over many years, may have a somewhat higher risk of bladder cancer, though other factors may contribute. The American Cancer Society summarizes the research on hair dyes and cancer.

8. Do power lines cause cancer?

Power lines produce low-frequency electric and magnetic fields. Electric fields are easily blocked by walls and other objects, and the magnetic fields are a weak, non-ionizing form of energy that doesn't damage genes. Exposure drops off quickly with distance, eventually matching normal household background levels. Directly beneath a power line, field strength is similar to what people encounter when using some household appliances.

What Actually Lowers Risk

The best-supported ways to reduce cancer risk are well known: avoid tobacco, limit alcohol, stay active, maintain a healthy weight and protect skin from the sun. Screening also matters, because it can catch some cancers early or even prevent them. Recommended screenings depend on age and risk, so talk with a health care provider about which are right for you. For people interested in imaging, preventive scans and dedicated tests such as lung imaging are options to discuss alongside standard screening. The Advanced Body Scan FAQ explains what imaging can and can't find.